Photoelectron Momentum Distribution Of Hydrogen-like Atom In Linearly Ionized Strong Radiation Field

Because advanced technology about laser have been improved over the past years dramatically,the strong field physics causes public concern and an increasing number of researchers pour their attention into the investigation such as above threshold ionization(ATI),double ionization(DI),and high-order harmonic generation(HHG)associated with strong field physics.Significantly,an meaningful theory named strong-field approximation(SFA)provides us with an insightful method to understand photo-ionization process of atoms and molecules.On the contrary,a series of new experiments challenge this theory apparently.Experiments related to photoelectron longitudinal momentum distribution threaten to the dipole approximation which stimulates us to find feasible method to deal with non-dipole approximation based on SFA theory.Initially,we raise a alternative method to research photoelectron longitudinal momentum distribution in tunneling regime based on SFA theory.Through this investigation,we find that the momentum distribution in direction of beam propagation is asymmetry including linear polarization and circular polarization.We contain spatial variable in vector potential and introduce correction of short Coulomb potential range which demonstrate breakdown of dipole approximation is the major reason of shift of peak in photoelectron longitudinal momentum spectra fully.One further issue is that I consider influence of Coulomb potential in SFA and research the photoelectron perpendicular momentum distribution in detail.Through introducing Green function in Kramers-Henneberger frame,a minimal centre with a series of discrete peaks has been found in photoelectron perpendicular momentum distribution.One last point is that characteristic peaks has been observed in low energy structure(LES)when SFA with Coulomb potential is adopted to research the issue.The Keldysh parameter exerts influence on the unusual structure extremely.Indeed,the low energy structure corresponds to photoelectron perpendicular momentum distribution as others report.